Display Apparatus

1. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into N number of subfields each subfield having a period shorter than a period of each field, N being a positive integer of two or larger; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per N number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the N number of subfields are aligned from a first subfield to an N-th subfield in an image-displaying order, display periods of the subfields become longer from the first subfield towards the N-th subfield or from the N-th subfield towards the first subfield, a difference in display period between subfields adiacent to each other becomes smaller per at least one subfield as the display periods become longer, for specific gradation levels at which false contour effects have to be restricted, a specific subfield to be turned on is shifted by one subfield in the image-displaying order, or the specific subfield is kept on when the specific subfield is once turned on and one of subfields having shorter display periods than the specific subfield is turned on, per gradation-level change, for gradation levels except the specific gradation levels, a subfield to be turned on is shifted by at least one subfield in the image-displaying order, per gradation-level change, and wherein when a subfield having the longest display period among the N number of subfields is turned from off to on at a certain gradation level, the subfield thus turned on is kept on at gradation levels higher than the certain gradation levels.

2. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into N number of subfields each subfield having a period shorter than a period of each field, N being a positive integer of two or larger; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per N number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the N number of subfields are aligned from a first subfield to an N-th subfield in an image-displaying order, display periods of the subfields become longer from the first subfield towards the N-th subfield or from the N-th subfield towards the first subfield, a difference in display period between subfields adiacent to each other is constant over the N number of subfields, through the gradation levels, a specific subfield to be turned on is shifted by one subfield in the image-displaying order, or the specific subfield is kept on when the specific subfield is once turned on and one of the subfields having shorter display periods than the specific subfield is turned on per gradation-level change, and wherein when a subfield having the longest display period among the N number of subfields is turned from off to on at a certain gradation level, the subfield thus turned on is kept on at gradation levels higher than the certain gradation levels.

3. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into a specific number of subfields each subfield having a period shorter than a period of each field; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per specific number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the specific number of subfields are divided into a first subfield group and a second subfield group aligned in an image-displaying order, first subfields of the first subfield group are aligned from a first subfield to an N-th subfield in the image-displaying order, N being a positive integer of two or larger but smaller than the specific number, display periods of the first subfields becoming longer from the first subfield towards the N-th subfield whereas second subfields of the second subfield group that follows the first subfield group in the image-displaying order have a display period longer than the first subfields of the first subfield ground and constant over the second subfields, or the display periods of the first subfields of the first subfield group become longer from the N-th subfield towards the first subfield whereas the second subfields of the second subfield group that precedes the first subfield group in the image-displaying order have a display period longer than the first subfields of the first subfield ground and constant over the second subfields, through the gradation levels, a specific one subfield to be turned on or specific two subfields to be turned on are shifted by one subfield in the image-displaying order or the specific one subfield or the specific two subfields are kept on when once turned on and one of the subfields having shorter display periods than the specific subfield or the specific two subfields is turned on, per gradation-level change, and wherein when a subfield having the longest display period among all of the subfields in the first and second subfield groups is turned from off to on at a certain gradation level, the subfield thus turned on is kept on at gradation levels higher than the certain gradation level.

4. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into a specific number of subfields each subfield having a period shorter than a period of each field; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turn on and off the subfields in accordance with gradation levels of the digital video signal, an image being to be displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per specific number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the specific number of subfields are divided into a first subfield group, a second subfield group and a third subfield group aligned in an image-displaying order, the first subfield group preceding the second subfield group that precedes the third subfield group in the image-displaying order, first subfields of the first subfield ground are aligned from a first subfield to an N-th subfield in the image-displaying order, N being a positive integer of two or larger but smaller than the specific number, display periods of the first subfields becoming shorter from the first subfield towards the N-th subfield, third subfields of the third subfield group are aligned from a first subfield to an M-th subfield in the image-displaying order, M being a positive integer of two or larger but smaller than the specific number, display periods of the third subfields becoming longer from the first subfield towards the M-th subfield, and all of display periods of second subfields of the second subfield ground are shorter than a display period of the N-th subfield of the first subfield group and also a display period of the first subfield of the third subfield group, through the gradation levels, a specific one subfield to be turned on in the first subfield group is shifted by one subfield in the image-displaying order, or the specific subfield of the first subfield group is kept on when once turned on and one of the subfields in the second subfield group having a shorter display period than the specific subfield of the first subfield group is turned on, per gradation-level change, through the gradation levels, a specific one subfield to be turned on in the third subfield group is shifted by one subfield in the image-displaying order, or the specific subfield of the third subfield group is kept on when once turned on and one of the subfields in the second subfield group having a shorter display period than the specific subfield of the third subfield group is turned on, per gradation-level change, and wherein when a subfield having the longest display period in the first subfield ground is turned from off to on at a certain gradation level, the subfield thus turned on in the first subfield is kept on at gradation levels higher than the certain gradation level or when a subfield having the longest display period in the third subfield group is turned from off to on at a certain gradation level, the subfield thus turned on in the third subfield group is kept on at gradation levels higher than the certain gradation level.

5. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into a specific number of subfields each subfield having a period shorter than a period of each field; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per specific number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the specific number of subfields are divided into a first subfield group, a second subfield group and a third subfield group aligned in an image-displaying order, the first subfield group preceding the second subfield group that precedes the third subfield group in the image-displaying order, first subfields of the first subfield group have a display period constant over the first subfields, third subfields of the third subfield group have a display period constant over the third subfields, and second subfields of the second subfield group have display periods shorter than the display periods of the first and third subfields in the first and third subfield groups, respectively, through the gradation levels, a specific one subfield to be turned on in the first subfield group is shifted by one subfield in the image-displaying order per gradation-level change and at least one of the second subfields in the second subfield group is turned on when the specific one subfield of the first subfield group is shifted, through the gradation levels, a specific one subfield to be turned on in the third subfield group is shifted by one subfield in the image-displaying order oer gradation-level change and at least one of the second subfields in the second subfield ground is turned on when the specific one subfield of the third subfield group is shifted, and wherein when a subfield located first in the first subfield ground in the image-displaying order is turned from off to on at a certain gradation level, the subfield thus turned on in the first subfield group is kept on at gradation levels higher than the certain gradation level or when a subfield located last in the third subfield group in the image-displaying order is turned from off to on at a certain gradation level, the subfield thus turned on in the third subfield ground is kept on at gradation levels higher than the certain gradation level.

6. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into a specific number of subfields each subfield having a period shorter than a period of each field; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per specific number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the specific number of subfields are divided into a first subfield group, a second subfield group and a third subfield group, the second and third subfield groups being aligned in an image-displaying order, the second subfield group preceding the third subfield group in the image-displaying order second subfields of the second subfield group are aligned from a first subfield to an N-th subfield in the image-displaying order, N being a positive integer of two or larger but smaller than the specific number, display periods of the second subfields of the second subfield group becoming shorter from the first subfield towards the N-th subfield, first subfields of the first subfield group are dispersed into the second and third subfield groups and display periods of all of the first subfields are shorter than a display period of the N-th subfield of the second subfield group, third subfields of the third subfield group are aligned from a first subfield to an M-th subfield in the image-displaying order, M being a positive integer of two or larger but smaller than the specific number, display periods of the third subfields becoming longer from the first subfield to the M-th subfield, the first subfield of the second subfield group having the longest display period in the second subfield group is located at the ton of all of the subfields in the first, second and third subfield grounds whereas the M-th subfield of the third subfield ground having the longest display period in the third subfield group is located at the last of all of the subfields in the first, second, and third subfield groups, when all of the subfields in the first, second, and third subfield groups are divided into a former ground including the second subfield group and a latter group including the third subfield group in the image-displaying order, a total of the display periods in the former group and a total of the display periods in the latter group are almost equal to each other, through the gradation levels, a specific one subfield to be turned on in the second subfield group is shifted by one subfield in the image-displaying order, or the specific subfield of the second subfield is kept on when once turned on and one of the subfields in the first subfield group having a shorter display period than the specific subfield of the second subfield is turned on, per gradation-level change, through the gradation levels, a specific one subfield to be turned on in the third subfield group is shifted by one subfield in the image-displaying order, or the specific subfield in the third subfield group is kept on when once turned on and one of the subfields in the first subfield group having a shorter display period than the specific subfield of the third subfield group is turned on, per gradation-level change, and wherein when a subfield having the longest display period in the second subfield group is turned from off to on at a certain gradation level, the subfield thus turned on is kept on at gradation levels higher than the certain gradation level or when a subfield having the longest display period in the third subfield ground is turned from off to on at a certain gradation level, the subfield thus turned on is kept on at gradation levels higher than the certain gradation level.

7. A display apparatus comprising: a display unit having a matrix of multiple pixels; a divider to divide each of a plurality of fields of a digital input video signal into a specific number of subfields each subfield having a period shorter than a period of each field; a memory storing a look-up table to be used by the divider for dividing the field into the subfields, the look-up table listing data for selectively turning on and off the subfields in accordance with gradation levels of the digital video signal, an image being to-be displayed on the display unit when the subfields are selectively turned on; and a driver to drive the pixels of the display unit per specific number of subfields so that an image based on the digital input video signal is displayed on the display unit, wherein the data are arranged in the look-up table such that the specific number of subfields are divided into a first subfield group, a second subfield ground and a third subfield group, the second and third subfield groups being aligned in an image-displaying order, the second subfield group preceding the third subfield group in the image-displaying order, second subfields of the second subfield group are aligned from a first subfield to an N-th subfield in the image-displaying order, N being a positive integer of two or larger but smaller than the specific number, display periods of the second subfields of the second subfield group being constant over the second subfields, third subfields of the third subfield group are aligned from a first subfield to an M-th subfield in the image-displaying order, M being a positive integer of two or larger but smaller than the specific number, display periods of the third subfields being constant over the third subfields, first subfields of the first subfield group are dispersed into the second and third subfield groups and display periods of all of the first subfields are shorter than the display periods of the second and third subfields of the second and third subfield groups, respectively, the first subfield of the second subfield group is located at the top of all of the subfields in the first, second and third subfield groups whereas the M-th subfield of the third subfield group is located at the last of all of the subfields in the first, second, and third subfield groups, when all of the subfields in the first, second, and third subfield grounds are divided into a former ground including the second subfield group and a latter group including the third subfield group in the image-displaying order, a total of the display periods in the former ground and a total of the display periods in the latter group are almost equal to each other, through the gradation levels, a specific one subfield to be turned on in the second subfield group is shifted by one subfield in the image-displaying order and at least one of the first subfields of the first subfield group is turned on when the specific one subfield of the second subfield group is shifted, per gradation-level change, through the gradation levels, a specific one subfield to be turned on in the third subfield ground is shifted by one subfield in the image-dissolving order and at least one of the first subfields of the first subfield ground is turned on when the specific one subfield of the third subfield group is shifted, per gradation-level change, and wherein when the first subfield located at the ton of all of the subfields in the first, second and third subfield grounds is turned from off to on at a certain gradation level, the first subfield thus turned on is kept on at gradation levels higher than the certain gradation level or when the M-th subfield located at the last of all of the subfields in the first, second and third subfield groups is turned from off to on at a certain gradation level, the M-th subfield thus turned on is kept on at gradation levels higher than the certain gradation level.